1. Field of the Invention
This invention relates to a control device which automatically adjusts the boiler temperature in a forced hot-water heating system for improved economy.
2. Description of Prior Art
In forced hot-water systems used to heat buildings, both residential and commercial, the temperature of the water in the boiler is typically maintained by manually setting high-limit and low-limit controls, or a main temperature control in conjunction with a secondary adjustment which establishes the difference between the upper and lower temperatures. In some cases the users may make occasional changes in these adjustments on a seasonal basis but in most cases they remain fixed. In any event, the boiler temperature settings are seldom, if ever, changed often enough to preclude significant losses in heating system energy.
If the boiler temperature controls are set too high for the heating system's demands, radiation losses are increased and fuel is wasted. With settings too low, the system will not be able to maintain the temperatures set by the thermostats in the heated areas. Furthermore, the pumps used to circulate the heated water will be "on" excessively which adds to the overall costs in the form of increased energy usage. Also, maintenance costs are raised because the useful lives of the pumps are decreased.
The present invention computes, on a continuing basis, the operating costs of a forced hot-water heating system and uses those computed costs to automatically maintain control of the boiler temperatures at their optimum values to minimize overall heating system costs.
Some schemes to automatically set the temperature of boiler water of hot-water heating systems do not account for the costs of operating and maintaining the circulation pumps used in forced hot-water systems and therefore cannot minimize the overall costs of operating heating systems of this type.